Daniel dbawbaugh



TTIWBNTOR (No Model.)

VD'. DRAWBAUGH. g TBL-TTHONEV TRANSMITTER.

Patented Jan. 1, 1884.

u Unirse STATES Parana* Ormea..`

'DANIEL DRAVBAUGH, OF EBERLYS'MILL, PENNSYLVANIA, ASSIGNOR .TO

THE PEOPLES TELEPHONE COMPANY, OF NEY YORK.

'TELEPHONE-TRANSMITTER.

`EP.IGIFICATION forming part of Letters Patient No. 291,312, datedJanuary l, 1884-..

Application llcrl March 24, 1853. (No model.:

[To all whom t 11i/.tj concern:

Beit known that I, DANIEL DRAWBAUGH, of Eberlys Mill, Cumberland county,Pennsylvania, have invented a new and useful Improvement in rlelephoneTransmitters, of which the following is a speciiication.

My invention relates to that class of telephone-transmitters n which acurrent is modiied and rcnderedcapable of transmit-ting articulatespeech by passage through pieces of low conducting material in contact.The invention consistsin the construction of the instrument moreparticularly hereinafter set forth, and in the devices described,whereby the carbons may be adjusted in more or less delicate contact.

In the accompanying drawings, Figure l is an elevation of the instrumentwith the `back removed. Fig. 2 is a vertical section on the line a: :cof Fig. 1. Fig. 3 'is a horizontal section on theline 3/ y of` Fig. 1.

Similar' letters of reference indicate like parts.

A is the box or case of theinstrument.

B is the outer cover, having a mouthpiece orifice, C, and Dis thediaphragm. I have shown this diaphragm with a central perforation, E,covered by a piece of felt or similar material, F; but this constructionis not at all essential, inasmuch as I may use a solid cony tinuousdiaphragm without such perforation "bracket I pivot a metal cup, I.

or felt cover. I make said diaphragm preferably of `wood or othernon-conducting material, and to its rear side, and at about the center,I attach a metal bracket, G. To said Vithin said cup is inserted ahollow cylinder of carbon or other non-conducting material, J. At thebottom ofthe cup, and within the hollow of said cylinder, I place apiece of rubber or other insulating material, L.

`M is a cylinder, of carbon or otherlow conducting inateriahiittingloosely within the hollow cylinder I.

In the upper portion of cylinder M is rigidly secured a metal rod, N.The cup I is pivoted to the bracket G by means of ashaft, O, which isrigidly secured to the cup I, but passes loosely through the hole in thebracket G, and is prevented from coming out of said oriiice by the nutH. rIhis shaft extends through the side of the case A, as shown inpartial section, Fig. l, and has at its outer end alever, I). `It willbe obvious that when the cup I is caused to stand vertically the carboncylinder N will rest upon the piece of insulating material L at thebottom oi' the hollow of the cylinder J; hence the contact between thecarbon cylinder `M and the cylinder J will be avery light one,

inclination of the cup I; also, that said initial pressure will be lessas the cup approaches a vertical position and greater as it more nearlyapproximates a horizontal position. A very convenient means is thereforeafforded by this device ol' adjusting the telephone so that it shall beas sensitive as may be desired, this adjustment being effected by simplyturning a lever, I?, which is outside of the case ofthe instrument, andthus altering the inclination y ofthe cup I.

The circuits in the instrument proceed as follows: from the battery tothe binding-post l. to the primary of the :induction-coil Q,by the wirea, to the rod N, carbon M, carbon J, cup I, and bracket G, by the wirebto the spring R; thence to the plate S, binding-post 2, and battery. Thesecondary wires c d of the induction-coil lead to the line binding-posts3 and Ll. From said wires branch wires of lead to the bindingpost 5 and6, to which a receiving-instruinent may be attached.

T is a hook or bracket to support a recciv- IOO attached to and upon amovable support and surrounding the first electrode, and means forvarying the inclination of the second electrode and support, so thatsaid second electrode may sustain more or less of the weight of thefirst electrode, substantially as described.

2. In a telephone-transniittcr, the combination of an electrode of lowconducting,` material in the forni of a hollow cylinder, verticallydisposed, having a piece of insulating material inserted in its lowerend and sustained by a support, and a second electrode of low conductingmaterial in the forni of a solid eylinder, adapted to fit loosely in thefirst electrode and to rest on said inserted piece of insulating,`material, and means for adjusting said first electrode and support at adesired inclination, so as to vary the proportion of weight of thesecond electrode respectively sustained by the :first electrode,substantially as described.

3.' In a telephone-transmitter, the combination of a diaphragm, a hollowcylinder of low conducting` material held in a support hinged or pivotedto said diaphragm, asolid cylinder of low conducting material looselytting` in said hollow cylinder, and a means for turning said hollowcylinder on its pivot or hinge, substantially as described.

4. In a telephone-transmitter, a diaphragm of non-conducting material, ametal cup pivoted to said diaphragm, a hollow cylinder of low conductingmaterial contained in said cup, a solid cylinder of low conducting,`material loosely itting` in said hollow cylinder, a piece ofinsulating,` material arranged between the lower end of said solidcylinder and the cup, and means for turning said'cup on its pivot o1'hinge. substantially as described.

5. In a telephone-transmitter, the combina tion of a diaphragm ofnon-conducting material, bracket G, cup I, carbon J, carbon M. rod O,and lever l?, substantially as described.

DANIEL DRAVBAUGH.

itnessesz W. H. CLENDENIN, JOHN L. SHELLEY.

